1. Field of the Invention
The present invention relates to ultrasonic wave fuel injection and supply devices, and more particularly to such a device in which liquid fuel is supplied under pressure to an ultrasonic vibratory member, of a hollow, cylindricaly shaped body, positioned within an intake passage of an internal combustion engine, the fuel thus supplied being instantaneously atomized due to the ultrasonic vibration of the hollow cylindrically shaped body so as to be subsequently mixed with air and followed by the supply thereof, in a uniform air-fuel mixture, into the combustion chamber of the engine.
2. Description of the Prior Art
Prior art fuel injection devices for use in internal combustion engines provide many advantages in engine performance and purification of the exhaust gases, since the aforenoted devices provide uniform distribution of the air-fuel mixture to the respective cylinders in a multiple cylinder type engine, as well ss the precise control of the air-fuel ratio of the charge mixture to be supplied to the engine in accordance with the running conditions of the engine.
Such prior art fuel injection devices, however, intend to atomize the fuel by injecting the same under pressure through a nozzle having a minute exit for atomizing the fuel due to shear forces impressed upon the fuel, caused by frictional resistance between the injected fuel and the surrounding air. The prior art fuel injection devices thus fail to meet success in injecting fuel under such desired high pressures, that is, the injection speed of the fuel through the nozzle is low, resulting in a failure to provide the fine particles of fuel having a minute size. In addition, the prior art fuel injection devices pose another shortcoming in that because of the failure to achieve the uniform shear forces of the fuel caused by the frictional resistance between the injected fuel and air, there results a lack of uniformity in size of the fuel particles atomized. It follows from this that the prior art fuel injection devices impair the desired running performance of the engine using a charge mixture having a high air-fuel ratio, because of the insufficient production of a uniform lean charge mixture.
An attempt to further reduce the size of the fuel particles atomized necessarily leads to an increase in the injection pressure of the fuel, and this dictates the provision of a high pressure pump. As a result, the size of the pump must be increased, and hence, a high manufacturing cost results, with an accompanying increase in load imposed upon the internal combustion engine. Still further, the prior art fuel injection devices fail to reduce the amount of harmful gases to the desired extent, because of the large average size of the particles of atomized fuel generated and the distribution of the size of such fuel particles over a wide range.